“MY KNOB”

front

Four LEDs and push buttons are on the top. The other four push buttons are around the wheel.

This accessory for the SDR transceiver was homebrewed mainly for portable microwave operation where it replaces the mouse. Although the mouse works great for operation inside the shack (my personal opinion), when portable on the top of a mountain it becomes a bit dodgy experience (read: frozen hands and winter gloves). It has one aluminium wheel, 8 pushbuttons and 4 LEDs.  Inside an ATMEGA16 microcontroller runs the whole show. The wheel utilizes an AMS AS5040 hall effect sensor which detects the angular position of a magnet located inside the wheel’s axis. The wheel itself rotates inside double ball bearings offering low friction. The microcontroller communicates with the computer via a FTDI UM232R USB module. Power is drawn from the USB port. The enclosure is made from 1mm sheet metal, welded with a MIG, drilled and painted black. Communication with PowerSDR is accomplished using CAT commands. The current firmware (V1.0) is written in Bascom-AVR and offers the basic needed functionality when portable (frequency tuning, frequency tuning step, output power, AF gain, band change and audio mute)

back

The USB port on the back side is visible.

components

All components are visible. The USB module (right) is attached to the metal plate which doubles as a support of the top PCB (the one with the LEDs).

sensor

The AS5040 chip is visible with the magnet about 1mm above it.

bearing

One of the two ball bearings is visible. The square block is attached to the enclosure. The wheel is attached to the protruding shaft.

knob

The wheel is 6cm in diameter and is machined of aluminium.